An electronic device having a power conversion device for driving a motor is mounted on a hybrid vehicle or an electric vehicle. An electronic device provided with a power conversion device converts DC power supplied from a power supply battery into AC power to drive a motor. On the contrary, the power conversion device converts AC power regenerated by the motor into DC power and stores the DC power in an electric storage device. A semiconductor device that generates heat at a high temperature is housed inside a case of such an electronic device, and immersed in a cooling medium such as cooling water and cooled.
Up to now, a power semiconductor device has been known in which a semiconductor element such as an IGBT is sealed with a resin and a surface of the device that comes into contact with a cooling medium is covered with a metal film. In that structure, with the formation of the metal film, heat dissipation is improved, and a waterproof property against the cooling medium is enhanced (refer to Patent Literature 1).